Figure 4
From: Repeated radiation damage and thermal annealing of avalanche photodiodes
Dark count rates measured on DM2 after each irradiation and conditional annealing for increasing cumulative proton radiation fluence. All characterization is performed at a detector temperature of −80∘C. Thermal annealing at +80∘C for one hour is performed only if the measured dark count rate after irradiation exceeds 2 kcps in at least two detectors, and at \(4\times 10^{9}\) p/cm2 (nominal end-of-mission—see text). In general, dark count rates are found to increase after each incremental irradiation and decrease after each annealing. Uncertainties, quantified by one standard deviation of Poissonian dark counts about the observed value, are smaller than the size of the marker symbols used in the graph